Seizures Flashcards
What are seizures?
Transient alterations in behaviour due to abnormally excessive and synchronous neuronal activity in the brain.
What is epilepsy?
Disorder characterized by frequent seizures.
What is symptomatc epilepsy?
Epilepsy caused by a brain injury.
What is asymptomatic epilepsy?
Epilepsy due to genetic predispositions.
How are seizures provoked?
Drugs and electrical stimulation?
What is surround inhibition?
The activity of one neuron will inhibit the activity of surrounding neurons to prevent overactivated synchronous activity and increase focused activity.
What are the three stages of a seizure?
Initiation, propagation, termination.
How are seizures initiated?
Sustained depolarization of neurons leads to calcium influx through NMDA receptors, causing high-frequency bursts of action potentials and hyper synchronization of neuronal propagation.
How are seizures propagated?
Extracellular potassium increases to prevent hyperpolarization. Accumulation of calcium in presynaptic cells enhances neurotransmitter release.
How are seizures terminated?
Mechanisms aren’t completely known, but relate to loss of ion gradients, loss of ATP, depletion of glutamate neurotransmitters, and activation of GABA.
What is status epilepticus?
Seizures lasting longer than five minutes, or when multiple seizures happen in less than five minutes.
What is the postical period?
Period after a seizure characterized by confusion, depression, fatigue, and possible psychosis.
What are the three classes of seizures?
- Focal seizures.
- Generalized seizures.
- Non-convulsive seizures.
What are simple focal seizures?
A focused seizure in which consciousness is not lost.
What are complex focal seizures?
A focused seizure in which consciousness is lost.
What is a focal seizure?
Seizure in which only a specific area of the brain experiences hyperactivity.
What is a Jacksonian March?
The gradual expansion of contraction in a muscle into other muscle groups.
What are automatisms?
Unusual activities not consciously produced.
Can focal seizures advance into generalized seizures?
Yes.
What are generalized seizures?
Seizures that spread from a localized area in the brain.
Are generalized seizures always complex?
Yes.
What is a tonic-clonic seizure?
A period of muscle contraction followed by a period of alternating between contraction and relaxation.
What is a myoclonic seizure?
A seizure in which there is a brief shock like contraction.
What are non-convulsive seizures?
Seizures in which there no muscle contractions. Can be absence or atonic seizures.
What are absence seizures?
Abrupt impairment of consciousness, but an individual does not typically fall over.
What are atonic seizures?
Sudden loss of muscle strength, yet the individual usually maintains consciousness.
What are the two categories of antiseizure medication?
- Medication that enhances inhibitory neurotransmission.
2. Medication that diminishes excitatory neurotransmisison.
What is benzodiazepine?
Antiseizure medication that is a positive allosteric modulator at GABA receptors. Increase frequency of receptor opening (increases potency).
What are barbituates?
Antiseizure positive allosteric modulator of GABA receptors that can act as an agonist at high enough concentrations. Increases the amount of time that GABA receptors are open in order to increase efficacy of GABA. Poses risk of overdose.
What is vigabatrin?
Antiseizure medication that enahnces GABA transmission in presynaptic cell by inibiting GABA-T (GABA enzyme)
What is tiagabine?
Antiseizure medication that inhibits the GABA reputake transporter GAT-1.
What is carbamazepine?
Antiseizure medication that blocks voltage gated sodium channels by creating conformational changes in the inactivation gate. Is dependant on rate so as to avoid inactivation in innapropriate regions.
What is gabapentin?
Centrally active antiseizure medication that activates GABA receptors (able to cross BBB). Also inhibits calcium channels to reduce excitatory neurotransmitter release.
What is perampanel?
Non-competitive antagonist at AMPA receptors to alleviate epilepsy. Nonselective, causes psychoactive adverse effects.
What is the main worry/adverse effect of antiseizure medication?
Most on non-specific and therefore cause CNS depression.
